Packaging

ABSTRACT

A method and apparatus for applying a tie around the gathered open end or neck of a bag to close the bag. A feed device ( 6 ) feeds a length of tie material ( 1 ) to a former ( 3 ) where the tie material is formed into a tie loop ( 2 ) around the gathered open or neck of a bag inserted in the former ( 3 ). After forming the tie loop ( 2 ), a leading, free end of the tie material  1  is held in a gripper device ( 14 ) and the feed device ( 6 ) for the tie material ( 1 ) reversed to pull the tie material and close the tie loop ( 2 ) around the gathered open end or neck of the bag. A cutter device cuts the tie material ( 1 ) after the tying operation to allow the bag to be removed from the former ( 3 ) with the tie secured thereto. A guard ring ( 16 ) prevents tightening of the tie loop and requires the operator to use both hands to initiate removal of the guard ring so that the tie loop ( 2 ) cannot be tightened with a part of the operators hand or fingers in the former ( 3 ). In one embodiment, the gathered open end or neck of the bag is inserted into the former ( 3 ) with a vacuum device.

This invention concerns improvements in or relating to packagingcontainers, especially containers such as bags, sacks, pouches and othersimilar containers, and to apparatus for closing such containers toretain the contents therein. For convenience, the term “bag” is usedhereinafter and it will be understood that this term includes anysimilar type of container.

The invention has particular, but not exclusive, application to bags forfood products and is especially useful for packaging food products thatare to be cooked in the bag. One such application is the bags ofplastics material typically used to contain chickens while they arebeing cooked.

Previous methods of closing plastic bags have included heat sealing butproblems can arise when heat sealing bags containing chickens to becooked in the bag. Grease transferred from the chicken to the plasticsmaterial of the bag during the packaging process can impair the heatsealing process producing a partial or incomplete seal. As a result, thebag may leak allowing fat and other liquids produced during the cookingprocess to escape. Also, because the bag is not sealed, there is a riskof contamination of the cooked chicken with airborne bacteria or thelike entering the bag.

Another commonly employed method of closing plastic bags has made use ofmetal clips that are pressed around the gathered open end or neck of thebag. Such metal clips are effective to close the bag even if grease ispresent on the plastics material of the bag. However, where metal clipsare used to close bags containing chickens to be cooked in the bag, themetal clips become very hot during the cooking process and can melt theplastics material of the bag producing a hole resulting in the sameproblems and disadvantages arising from partial heat sealing of plasticbags discussed above.

Furthermore, it is common to check food products for the presence offoreign metal objects in the food that would present a health and safetyrisk to the consumer. Usually, the product is scanned with a metaldetector and this gives rise to a problem if metal clips are used toclose the bag. Plastic clips avoid this problem but the manufacture anduse of such clips adds to costs.

The present invention has been made from a consideration of theforegoing problems and disadvantages.

According to a first aspect of the present invention we provide aclosure for a bag comprising a flexible tie of plastics materialconfigured to form a double knot around a gathered open end or neck of abag to close the bag.

Preferably, the tie comprises a length of plastics of substantiallyuniform cross-section, typically circular which may be formed byextrusion.

Preferably, the plastics material of the tie is coated with a plasticsmaterial that softens or melts during the tying operation and sets toprevent the knot being undone.

According to a second aspect of the present invention we provideapparatus for applying a tie to a bag to close the bag, the apparatuscomprising a former configured to receive a length of tie material andform the tie material into a tie loop, and means for tightening the tieloop around a gathered open end or neck of a bag to close the bag andsecure the tie.

Preferably, the former comprises an annular ring member with an internalsurface defining an opening in which the gathered end or neck of a bagcan be inserted, and the internal surface has a groove configured toform the tie material into the tie loop. In this way, when the tie loopis tightened the loop contracts to form the tie around the gathered openend or neck of the bag received within the tie loop. As a result, thetie loop can adapt to form different sizes of tie according to the sizeof the open end or neck of the bag inserted into the former. Thegathered open end or neck of the bag may be inserted in the formerbefore forming the tie loop but is more preferably inserted afterforming the tie loop.

Preferably, the groove extends circumferentially around the internalsurface for substantially two complete turns that cross-over at aplurality of circumferentially spaced apart locations. In this way, whenthe tie loop is tightened, the tie material forms a knot where the turnscross-over and the tie loop is preferably configured to secure the tiewith a double knot.

Preferably, one end of the groove is arranged to receive a leading endof the tie material from a feed device and the other end of the grooveis arranged to deliver the leading end to a gripper device. In this way,the tie loop is forced to contract and form the tie around the gatheredopen end or neck of the bag when the tie loop is tightened.

Preferably, the feed device is reversible to tighten the tie loop toform the tie when the leading end of the tie material is held by thegripper device. In this way, the same device can be used both to formthe tie loop and then tighten the tie loop to form the tie.

Preferably, the feed device includes a guide pulley and a drive beltarranged to grip the tie material between the guide pulley and drivebelt. In this way, rotation of the guide pulley in one direction feedstie material to the former and rotation of the guide pulley in theopposite direction tightens the tie loop.

Preferably, a cutting device is provided to cut the tie material betweenthe feed device and the former. In this way, the bag can be removed fromthe former with the tie secured to close the bag and the feed deviceoperated to feed the tie material to the former to form the next tieloop.

Preferably, a continuous length of tie material is stored on a reel ordrum and the feed device is arranged to receive the tie material fromthe reel or drum and feed the tie material to the former. In this way,the required length of tie material to form the tie loop can be fed tothe former and, after tightening, the tie material is cut ready to feedthe next length of tie material to the former.

Preferably, the former is provided with a guard ring received in theopening in a first position preventing the tie loop being tightened andthe guard ring is movable to a second position allowing tightening ofthe tie loop. In this way, the tie loop cannot be tightened until it isdesired to form the tie.

Preferably, the guard ring covers the groove in the first position andis clear of the groove in the second position. In this way, the guardring may assist formation of the tie loop by confining the leading endof the tie material to follow the groove as it is fed through the formerby the feed device.

Preferably, the tying operation requires the operator to use both hands,for example to operate two switches—one for each hand—within apre-determined time. In this way, the operator cannot start the tyingoperation while placing the gathered open end or neck of a bag in theformer and therefore the risk of the tie loop being tightened while partof the operators hand or fingers is in the former is reduced oreliminated.

Preferably, an insertion device is provided to assist in locating thegathered open end or neck of a bag in the former. In this way, theoperator does not have to place any part of their hand or fingers intothe former.

Preferably, the insertion device is a vacuum device that draws thegathered open end or neck of a bag into the former. In this way, theoperator can present the gathered open end or neck of a bag to theformer and operate the vacuum device to draw the bag into the former.

Preferably, the vacuum device is arranged to draw the gathered open endor neck of a bag a pre-determined distance into the former. In this way,the bag can be located in the correct position for attaching the tie.

Preferably, the vacuum device incorporates the guard ring to prevent thetie loop being tightened until the bag is located in the correctposition and the guard ring is withdrawn.

Preferably, the tie material is made of plastics, for example polyamidesuch as nylon although other plastics materials may be used according tothe requirements of a given application. In some applications, the tiematerial may be made of metal, for example wire, which may be coatedwith plastics material. Metal wire or plastics coated metal wire may beemployed where the packaging does not require checking for foreign metalbodies in the packaged product, for example non-food products.

According to a third aspect of the present invention, we provide amethod of closing a bag with a tie comprising the steps of providing atie material, forming the tie material into a tie loop in which the tiematerial crosses over at a plurality of circumferentially spacedpositions, and tightening the tie loop to form and secure a tie aroundthe gathered open end or neck of a bag received in the tie loop to closethe bag.

Preferably, the tie loop comprises substantially two complete turns thatcross-over to form a double knot to secure the tie when the tie loop istightened. In this way, the tie is secured in a reliable manner thatreduces the risk of the bag opening.

Preferably, the tie is formed by feeding a leading end of the tiematerial through a former to form the tie loop and gripping the leadingend of the tie material while applying a force to the tie material totighten the tie loop. The gathered open or neck of the bag may beinserted in the former before forming the tie loop but is morepreferably inserted after forming the tie loop.

Preferably, the tie material is fed to the former from a continuouslength of the tie material and the continuous length is cut after thetie is formed to release the bag. In this way, a plurality of ties canbe formed consecutively from one continuous length of tie material.

Preferably, the tie is made entirely of plastics material although othermaterials including metal wire or plastic coated metal wire may beemployed for certain applications.

According to a fourth aspect of the present invention, we provide aclosure for a bag comprising a flexible tie having an outer surface of aplastics material that softens or melts during a tying operation to forma knot and hardens or sets to prevent the knot being undone.

The tie may have a core made of plastics material and the outer surfacemay be made of the same or different plastics material. Alternatively,the tie may have a core of metal or alloy having a coating of plasticsmaterial forming the outer surface.

The invention will now be described in more detail by way of exampleonly with reference to the accompanying drawings wherein:

FIG. 1 is a side view of a bag tying machine embodying the presentinvention;

FIG. 2 is an enlarged detailed view of the circled area A in FIG. 1;

FIG. 3 is a perspective view, to an enlarged scale, of the former forthe tie material 1 shown in FIGS. 1 and 2;

FIG. 4 is a perspective view of one half of the former shown in FIG. 3;

FIGS. 5 a,5 b,5 c are side, end and plan views, to a reduced scale ofthe former half shown in FIG. 4;

FIG. 6 is a perspective view of the other half of the former shown inFIG. 3;

FIGS. 7 a,7 b,7 c are side, end and plan views, to a reduced scale ofthe former half shown in FIG. 6;

FIGS. 8 a,8 b,8 c are perspective views, to a reduced scale, showingformation of the tie material 1 loop in the former of FIG. 3;

FIGS. 9 a,9 b,9 c,9 d are views, to a reduced scale, of the tie material1 loop produced in the former of FIG. 3; and

FIG. 10 shows a modification to the bag tying machine of FIG. 1.

Referring to FIGS. 1 to 9 of the accompanying drawings, there is shown amachine 100 for applying a tie around the gathered open end or neck of abag (not shown) to close the bag by forming a length of tie material 1into a tie loop 2 in a former 3, inserting the gathered open end or neckof the bag into the tie loop 2, tightening the tie loop 2 about thegathered open end or neck of the bag to secure the tie, and cutting thetie material 1 to release the bag with the tie secured to close the bag.

As best shown in FIGS. 1 and 2, the former 3 is mounted in a block 4 andthe tie material 1 is supplied to the former 3 through a bore 5 in theblock 4 by a reversible feed mechanism 6 described in more detail later.A cutter device (not shown) is mounted in a bore 7 transverse to thebore 5 for cutting through the tie material 1 after the tie has beensecured to close the bag. The cutter device may be operated manually orautomatically on completion of the tying operation described in moredetail later.

As best shown in FIGS. 3 to 7, the former 3 is in the form of an annularring-shaped component 8 which in this embodiment is formed in two halves8 a,8 b each made by laser sintering although other methods of producingthe former 3 may be employed. The former 3 is provided on the internalsurface 9 with a groove 10 that extends circumferentially forsubstantially two complete turns 10 a,10 b around the internal surface 9of the former and crosses-over itself at four points 11 a,11 b,11 c,11 dspaced apart in the circumferential direction.

Referring now also to FIGS. 8 a,8 b,8 c, tie material 1 enters thegroove 10 at one end through a hole 12 in the former 3 that is alignedwith the bore 5 in the block 4. The tie material 1 is guided around theinternal surface 9 within the groove 10 to form the tie loop 2 and exitsthe groove 10 at the other end through a hole 13 in the former 3. Thehole 13 is counterbored at the outer end to provide a seating for aspring-loaded gripper device 14 that is received in the block 4 andholds the leading end of the tie material 1 during the tying operationdescribed later.

Referring now also to FIGS. 9 a,9 b,9 c,9 d, the tie loop 2 is formedwith two substantially complete turns 2 a,2 b that cross-over at fourpoints 15 a,15 b,15 c.15 d where the groove 10 in the internal surface 9of the former 3 crosses-over. The cross-over points 15 a,15 b,15 c,15 dform a double knot when the tie loop 2 is tightened to secure the tie asdescribed later.

The tie material 1 is made of a material that is relatively stiff in alongitudinal direction and flexible in a direction transverse thereto sothat, when the tie material 1 is fed through the former 3 it follows andconforms to the shape of the groove 10. The former 3 is also providedwith an internal guard ring 16 that prevents the tie loop 2 beingtightened until the guard ring 16 has been withdrawn from the former 3as described later and confines the tie material 1 to follow the groove10 in the internal surface 9 of the former 3 to assist forming the tieloop 2.

In this embodiment, the tie material 1 is made of plastics material, forexample polyamide such as nylon although this is not essential and otherplastics material such as polyester and copolymers of two or moreplastics materials may be employed. The tie material 1 is typically asingle filament but this also is not essential and the tie material 1may comprise two or more filaments of the same or different materialswould to form a cord.

Referring now to FIGS. 1 and 2 again, the feed mechanism 6 has a forwarddrive mode of operation and a reverse drive mode of operation. Theforward drive mode of operation is used to form the tie loop 2 byunwinding the tie material 1 from a storage drum or reel (not shown),feeding the tie material 1 through the bore 5 in the block 4 into theformer 3, around the groove 10 in the former 3 to form the tie loop 2,and then out of the former 3 into the gripper device 14 to grip and holdthe leading end of the tie material 1.

The reverse drive mode of operation is used to tighten the tie loop 2 toform and secure the tie around the open end or neck of a bag insertedinto the former 3.

The feed mechanism 6 includes an endless drive belt 17, a drive pulley18, a tensioning pulley 19 and three guide pulleys 20,21,22. The drivebelt 17 is passed around the pulleys as shown and has teeth (not shown)on one side that mesh with teeth (not shown) provided on the drivepulley 18, and the upper and lower guide pulleys 20,22 to provide apositive drive and prevent the belt 17 slipping. The other side of thebelt 17 is smooth and the tensioning pulley 19 and middle guide pulley21 have smooth outer surfaces that engage the smooth side of the belt17.

Operation of the machine to secure the open end or neck of a bag with atie will now be described. The operation includes a first stage in whichthe tie loop 2 is formed, a second stage in which the tie loop 2 istightened and a third stage in which the tie material 1 is cut torelease the bag with the tie applied and secured to close the bag.

In the first stage, a continuous length of the tie material 1 passesfrom the storage reel or drum to a U-shaped guide tube 23 that deliversthe tie material 1 to the middle guide pulley 21 where it is grippedbetween the opposed smooth surfaces of the middle guide pulley 21 andthe belt 17. The tie material 1 is drawn around the middle guide pulleyby the belt 17 to deliver the tie material 1 to the bore 5 in the block4 and feed the tie material 1 through the former 3 to the gripper device14 when the drive pulley 18 is rotated by the motor to drive the belt 23to rotate the middle guide pulley 21 in a clockwise direction as viewedin FIG. 1.

The gripper device 14 has a spring loaded jaw 24 that is held openagainst the biasing of a spring 25 as the leading end of the tiematerial 1 is fed through the former 3 and closes to grip and hold theleading end when it exits the former 3. The feed mechanism 6 isresponsive to the jaw 24 closing to shut-off the motor and stop feedingthe tie material 1 to the former 3. The tie loop 2 is now formed and themachine 100 is ready to insert the open end or neck of a bag into theformer 3 for the second stage of tightening the tie loop 2 to close thebag.

After the open or neck of the bag has been inserted in the former 3, theoperator can start the second stage in which the guard ring 16 iswithdrawn from the former 3 and the motor is started to rotate the drivepulley 18 in the opposite direction reversing the feed mechanism 17 andcausing the tie material 1 to be pulled in the opposite direction byrotation of the middle pulley 21 in the anticlockwise direction asviewed in FIG. 1 to tighten the tie loop 2 and close the bag.

This requires the operator to use both hands to actuate two switches—onefor each switch—within a pre-determined period of time, typically 0.5seconds before the tying operation is carried out. In this way, theoperator's hands are clear of the former 3 before the guard ring 16 iswithdrawn and the tie loop 2 tightened thereby preventing the tie loop 2being tightened while a part of the operators hand or fingers is withinthe former 3.

The drive mechanism 17 is responsive to any suitable means for detectingwhen the tie loop 2 has been tightened to close the bag, for example byincrease in tension in the tie material 1 when the tie is formed, toshut-off the motor and stop pulling the tie material 1. The tie is nowformed and the machine 100 is ready for the third stage of cutting thetie material 1 to release the bag.

In the third stage, the operator actuates the cutting device to cutthrough the tie material 1 in the bore 5 between the guide pulley 21 andthe former 3. The leading end of the tie material 1 is released beforeor after cutting the tie material 1 by opening the jaw 24 allowing thebag to be removed from the former with the tie secured to close the bag.The guard ring 16 returns to its position within the former 3 and themachine 100 is now ready for the first stage of forming the next tieloop 2.

The arrangement of the groove 10 in the former 3 to cross-over the tiematerial 1 produces a double knot when the tie loop 2 is tightened thatensures the tie is secured in a reliable manner. In this embodiment, thetie material 1 is also coated with a material that softens or meltsunder the heat generated by the friction created when the tie loop 2 istightened and sets so that the knots cannot be released.

In this way, the bag is effectively secured and maintained closed untilit is desired to open the bag, for example by cutting through the tiematerial 1 or cutting through the material of the bag itself to removethe portion secured by the tie. This is not essential, however, and thecoating material may be omitted.

As will now be appreciated, the present invention provides apparatus forapplying a tie to close a bag in a secure manner where the tie isproduced from a length of tie material that is formed into a tie loopand then tightened to form the tie. In this way, the tie can be madeusing low cost materials such as a plastics filament or metal wire. Thetie is secured with a double knot that reduces the risk of the tiecoming undone when formed from plastics material due to the resilienceof the plastics material.

Referring now to FIG. 10 of the drawings, there is shown a modificationto the machine shown in FIG. 1 in which like reference numerals are usedto indicate corresponding parts.

In this modification, a tie loop 2 is produced in a former 3 asdescribed previously and a vacuum insertion device 30 is provided todraw the gathered open end or neck of a bag (not shown) to be tied intothe former 3 so that the operator does not have to place any part oftheir hand or fingers into the former 3 to position the bag for tying.

The vacuum insertion device 30 includes a vacuum box 31 provided with anozzle 32 for connection to a vacuum pump (not shown) for exhausting airfrom box 31. A guard ring 16 is provided by a distal end of a tubularinner sleeve 33 that is received in a tubular outer sleeve 34 attachedto the box 31 in a fluid-tight manner by a securing ring 35 and anO-ring 36. A filter 37 provided at the proximal end of the inner sleeve33 is located by a securing ring 38 and acts as a stop to limitinsertion of the gathered open end or neck of the bag from the opendistal end of the inner sleeve 33. The bore of the inner sleeve 33 istapered in the direction of insertion to assist in retaining the openend or neck of the bag in its gathered state.

In use, the operator presents the gathered open end or neck of the bagto the former 3 with the inner sleeve 35 advanced to cover the tie loop2 to prevent the tie loop 2 being tightened. A vacuum is applied to thevacuum box 31 causing the gathered open or neck of the bag to be drawninto the inner sleeve 35 until it contacts the filter 37. In this way,the gathered open end or neck of the bag is drawn into the inner sleeve35 a pre-determined distance that locates the bag at the requiredposition for tying with the tie loop 2. The inner sleeve 35 is thenretracted by any suitable means such as a pneumatic cylinder (not shown)to allow the tie loop 2 to be tightened around the gathered open end orneck of the bag to close the bag and secure the tie. The tie material isthen cut and the bag removed from the former 3 as described previously.It will be understood that any other suitable device may be employed forpositioning the gathered open end or neck of the bag in the former.

The invention has particular application for use with bags used tocontain food products, especially food products to be cooked in the bagwhere it is desirable to prevent leakage of fluids from the bag andentry of contaminants into the bag. The invention is especially suitablefor tying plastic bags containing chickens while the chickens are beingcooked. The bags are made of food grade plastics materials capable ofwithstanding the cooking temperature without degrading and the ties arealso made of plastics material chosen to withstand the cookingtemperature. The packaging (bags and ties) is made entirely of plasticsand allows the use of metal detectors to scan the contents of the bagfor the presence of foreign metal bodies.

It will be understood that the invention has application for closing anyopen type packaging container with a tie and is not limited tocontainers for food products. Also, where detection of foreign metalbodies is not required, for example non food products, the tie may madeof other materials, for example metal wire or plastic coated metal wire.

1. Apparatus for applying a tie to a bag to close the bag, the apparatuscomprising a former configured to receive a length of tie material andform the tie material into a tie loop, and means for tightening the tieloop around a gathered open end or neck of a bag received within the tieloop to form and secure a tie closing the bag.
 2. Apparatus according toclaim 1 wherein, the former comprises an annular ring member with aninternal surface defining an opening in which the gathered end or neckof a bag can be inserted, and the internal surface has a grooveconfigured to form the tie material into the tie loop.
 3. Apparatusaccording to claim 2 wherein, the groove extends circumferentiallyaround the internal surface for substantially two complete turns thatcross-over at a plurality of circumferentially spaced apart locationswhereby, when the tie loop is tightened, the tie material forms a knotwhere the turns cross-over.
 4. (canceled)
 5. (canceled)
 6. Apparatusaccording to claim 2 wherein, one end of the groove is arranged toreceive a leading end of the tie material from a feed device and theother end of the groove is arranged to deliver the leading end to agripper device, the feed device and gripper device being configured suchthat the tie loop contracts and forms the tie around the gathered openend or neck of the bag when the tightening means is actuated. 7.(canceled)
 8. Apparatus according to claim 6 wherein, the feed device isreversible to tighten the tie loop to form the tie when the leading endof the tie material is held by the gripper device.
 9. Apparatusaccording to claim 8 wherein, the feed device includes a guide pulleyand a drive belt arranged to grip the tie material between the guidepulley and drive belt, and rotation of the guide pulley in one directionfeeds tie material to the former and rotation of the guide pulley in theopposite direction tightens the tie loop.
 10. (canceled)
 11. (canceled)12. Apparatus according to claim 6 wherein, the feed device is arrangedto receive tie material from a continuous length of tie material storedon a reel or drum and feed the tie material to the former, and a cuttingdevice is provided to cut the tie material between the feed device andthe former.
 13. Apparatus according to claim 2 wherein, the former isprovided with a guard ring received in the opening in a first positionin which the guard ring covers the groove preventing the tie loop beingtightened, and the guard ring is movable to a second position clear ofthe groove allowing tightening of the tie loop.
 14. (canceled) 15.Apparatus according to claim 13 wherein, the guard ring confines aleading end of the tie material to follow the groove as it is fedthrough the former.
 16. Apparatus according to claim 1 wherein, means isprovided for actuating the tying operation that is responsive to twooperations within a pre-determined time that requires the operator touse both hands, one for each operation.
 17. (canceled)
 18. (canceled)19. Apparatus according to claim 1 wherein, a vacuum insertion device isprovided that draws the gathered open end or neck of a bag into theformer, and wherein the vacuum device incorporates a guard ring toprevent the tie loop being tightened until the bag is located in thecorrect position and the guard ring is withdrawn.
 20. (canceled) 21.(canceled)
 22. A method of closing a bag with a tie comprising the stepsof providing a tie material, forming the tie material into a tie loop inwhich the tie material crosses over at a plurality of circumferentiallyspaced positions, and tightening the tie loop to form and secure a tiearound the gathered open end or neck of a bag received in the tie loopto close the bag.
 23. A method according to claim 22 wherein, the tieloop comprises substantially two complete turns that cross-over to forma double knot to secure the tie when the tie loop is tightened.
 24. Amethod according to claim 22 wherein, the tie is formed by feeding aleading end of the tie material through a former to form the tie loopand gripping the leading end of the tie material while applying a forceto the tie material to tighten the tie loop.
 25. A method according toclaim 24 including the step of cutting the tie material after the tie isformed, removing the bag from the former with the tie loop securedthereto, and feeding the leading end of the tie material through theformer to form a new tie loop for the next bag.
 26. (canceled) 27.(canceled)
 28. (canceled)
 29. A method according to claim 22 wherein,the tie is made of plastics material coated with a plastics materialthat softens or melts during the tying operation and sets to prevent theknot being undone.
 30. A method according to claim 29 wherein, the tiecomprises a length of plastics material of substantially uniformcircular cross-section.
 31. (canceled)
 32. (canceled)
 33. (canceled) 34.A method according to claim 22 wherein the tie is made of metal wire orplastic coated metal wire.
 35. A method according to claim 22 includingthe step of providing a guard for preventing tightening of the tiematerial until the guard has been removed.
 36. A method according toclaim 35 wherein the step of removing the guard requires two operationsby the operator—one for each hand—within a pre-determined period oftime.
 37. (canceled)
 38. (canceled)
 39. (canceled)
 40. (canceled)